Only synchronization requests waiting to be serviced can be canceled. To stop a synchronization that has already begun, use
the CancelSync(UInt32, Boolean) method.

You can use the ShutdownServer method and pass the DBSC_SHUTDOWN_CLEANLY type to cancel an active synchronization. Dbmlsync
attempts to cancel the synchronization before shutting down. This task is equivalent of cancelling a synchronization using
the DBTools interface.

A connection must be established to the server before this method can be used. This method cannot be used if the client has
disconnected from the server since the Sync method was called.